Summary

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Summary Applications (Synthesis) SN1 / E1 vs.
SN2 / E2
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E2 and E1 Reactions
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Substitution vs. Elimination
Alkyl halides can undergo SN2, SN1, E2 and E1
Reactions

• 1) Which reaction conditions favor SN2/E2 or
  SN1/E1?
• SN2/E2 reactions are favored by a high
• concentration of nucleophile/strong base
• SN1/E1 reactions are favored by a poor
• nucleophile/weak base

2) What will be the relative distribution of
substitution product vs. elimination product?
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Consider SN1/E1 vs. SN2/E2
Consider the Substrate
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NOTE a bulky base encourages elimination over
substitution
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Returning to Sn2 and E2Considering the
differences
Can you predict the products?
Can you explain the products?
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Substitution and Elimination Reactions in
Synthesis
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A hindered alkyl halide should be used if you
want to synthesize an alkene
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Which reaction produces an ether?
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Consecutive E2 Elimination Reactions Alkynes
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Intermolecular vs. Intramolecular Reactions

• A low concentration of reactant favors an
  intramolecular
• reaction
• The intramolecular reaction is also favored when
  a five-
• or six-membered ring is formed

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Three- and four-membered rings are less easily
formed Three-membered ring compounds are formed
more easily than four-membered ring
compounds The likelihood of the reacting groups
finding each other decreases sharply when the
groups are in compounds that would form
seven-membered and larger rings.
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Designing a synthesis
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